Backflow is the reverse flow of potentially contaminated liquid into the potable water supply.
The installation of a backflow prevention device protects the water supply from this very serious situation.
Backflow can occur when:
- the water delivery main (reticulation system) is at a lower pressure than a property’s plumbing system. This can occur when there is a burst in the supply main or excessive demand during fire fighting.
- a pump is connected to a property’s internal water plumbing system and is therefore using water at a pressure higher than the pressure in a water utility’s supply main.
- a pump is connected to a non-potable supply. Many rainwater tank installations are fitted with a pressure pump on the delivery side of the tank.
- high water usage downstream causes a pressure reduction upstream.
- the water outlet on a property is significantly higher than the water utility’s main with a constant back pressure.
- a bore water supply is connected to a property’s water supply system.
Read our Backflow Booklet(PDF, 2MB).
Go to NSW Water Directorate - Backflow Prevention and Cross Connection Guidelines.